The present invention relates to an improvement of a double side type flexible magnetic disc drive apparatus. More particularly, it relates to a mechanism for shifting one or both magnetic heads and to put it on and off a magnetic recording medium.
The mechanism of the conventional single side type flexible magnetic disc drive apparatus which is widely used will be illustrated as reference.
FIG. 1 shows a schematic view of the mechanism of the conventional flexible magnetic disc drive apparatus and FIG. 2 is sectional view of the mechanism thereof.
In FIGS. 1 and 2, a magnetic head (102) is fixed on a head carriage (101) which is shifted in the direction of the line A through a leading screw (104) by rotation of pulse motor (103). During a recording/reading out of data, a electric magnet (105) is energized, and a flexible recording medium (106) is pressed by a pad (108) mounted on arm (107) and the magnetic head (102) is caused to contact with the recording surface of the medium (106). The flexible recording medium (106) can be held out contact with the magnetic head (102) by lifting up the lift arm (109) at one end of the arm (107) and the pad (108), with a return spring (111) connected through the armature of the magnet which is not energized, and by a lever (110) during waiting or exchanging the recording medium (106). Reference numeral (112) designates a magnetic core of the magnetic head (102) and (113) designates a jacket covering the flexible recording medium.
As described above, in the conventional mechanism, the magnetic head (102) is fixed on the head carriage (101) and the flexible recording medium (106) is pressed by a felt like pad (108) from the rear surface of the recording medium at the corresponding position to attain the recording/reading out of data whereas the pad (108) is lifted up during the waiting time and the exchanging of the recording medium.
It has been considered to use both sides of the flexible magnetic disc recording medium and in that case, it is necessary to engage a pair of magnetic heads corresponding to both surfaces.
The double side type head carriage system has the structure shown in FIGS. 3 and 4 as a conventional embodiment.
FIG. 3 is a schematic view of one embodiment of the conventional double side type head carriage.
FIG. 4a is a sectional view of the head carriage of FIG. 3 in the recording/reading out condition and FIG. 4b is a sectional view of the head carriage of FIG. 3 in the waiting condition.
In FIGS. 3, 4a, and 4b, the reference numeral (1) designates a frame of the double side type head carriage and (2) designates a pair of double side type head sliders which are disposed to face each of the surfaces of the flexible recording medium (3); (4) designates a magnetic core of the double side type head slider (2); (5) designates a jacket covering the flexible recording medium (3); (6) designates leaf spring gimballing mechanisms equipping with the head sliders (2); (7) designates pressing mechanisms for pressing the head sliders (2) to the flexible recording medium (3). It is usual to use the head slider (2), the magnetic core (4), the leaf spring gimballing mechanism (6) and the pressing mechanism (7) as one of pair head assemblies. The head assembly is connected to a head shifting mechanism (8) with a screw (9). A supporting spring (10) is connected to the head shifting mechanism (8) having a lift arm (12) with a screw (11) and the other end of the supporting spring (10) is fixed on the frame (1). Reference numeral (13) designates an electric magnet; (14) designates a returning spring for lifting up the lift arm (12) by the lever (15) in the direction B during the waiting time or the exchanging of the flexible magnetic recording medium; (16) designates a projected part on one end of the head shifting mechanism (8) and the projected part is a hook for lifting up the head sliders (2) in the directions C, C to depart from the flexible magnetic recording medium (3) by hanging the pressing mechanism (7) of the head as shown in FIG. 4b during the waiting time for the recording/reading out or exchanging of the flexible magnetic recording medium.
In order to maintain the magnetic gap of the heads for both surfaces so as to contact with the flexible magnetic recording medium even though a curve or a wave of the flexible magnetic recording medium is found, each flat head slider (2) is disposed at each end of the leaf spring gimballing mechanism (6) and the head sliders (2) are pressed by the head pressing mechanism (7) in the directions D,D. During the waiting time for the recording/reading out or the exchanging of the flexible magnetic recording medium, the head upper and lower member (8) is shifted in the directions C,C by the lift arm (12) and the head pressing mechanism (7) is shifted by hanging a part of the head pressing mechanism by the projected part (16) and the leaf spring gimballing mechanism (6) is shifted by hanging it by a part of the head pressing mechanism (7) whereby the head slider (2) is shifted away from the flexible magnetic recording medium. The lift arm (12) is shifted by lifting the head lifting lever (15) in the direction B with the spring force of the returning spring (14) for the electric magnet (13). At the initiation of the recording/reading out, an attractive force is imparted by the electric magnet (13) to lower the head lifting lever whereby the lift arm (12) is shifted down as shown in FIG. 4a. The heads are lowered to contact with the flexible magnetic recording medium (3) by the spring force of the supporting spring (10) and the head pressing mechanism (7) except upon applying a lifting force to the head shifting mechanism (8) and the head pressing mechanism (7).
The magnetic heads (2) are shifted in the linear direction E through the lead screw (not shown) by the fixed pulse motor (not shown).
In the other embodiment of the double side type flexible magnetic disc drive apparatus, one fixed head used in the single side type apparatus shown in FIGS. 1 and 2 and one flat head slider disposed to face the fixed head shown in FIGS. 3 and 4 are shifted be lifted up and lowered by a lift arm.
In any of the double side type flexible magnetic disc drive apparatus, a pair of head sliders are faced to each other and lowered so as to contact them with the flexible magnetic recording medium or lifted up so as to separated them from the flexible magnetic recording medium. Accordingly, a pair of the hard head sliders impart shock by a collision through the flexible magnetic recording medium when the head sliders are lowered on each surface of the flexible magnetic recording medium. If the collision speed is high, the flexible magnetic recording medium is thus damaged. Upon the collision of the head sliders through the flexible magnetic recording medium, the head sliders are bounced to take certain time until settling to establish good contact of the head sliders with the flexible magnetic recording medium.
In the case of the single side type apparatus, the soft felt like substrate is used on the opposite surface, whereby such trouble is prevented.
In order to give a desired contacting accuracy for the magnetic gap, it is necessary to make the head slider with a hard substance.
In the case of the double side type apparatus, the positions of the magnetic gaps of the heads on both of the surfaces are usually shifted for a small distance of about 2.1 mm in the radial direction of the flexible magnetic recording medium. Accordingly, it is usually difficult to prevent the collision of the head sliders and the life of the flexible magnetic recording medium is, accordingly, usually shortened by the collision of the head sliders in the double side type flexible disc drive apparatus and the time required to reach stable contact of the head sliders with the recording medium is usually prolonged because of bouncing the head due to the collision.